OTV and route advertisements

[Jack Leung]

I'm sure this may have been addressed but I'm having trouble finding documentation for this scenario.    Let's say you do setup OTV for two data centers with the intention to extend a vlan across both.   Let's say we populate this with a /24 subnet so that you have hosts living on both data centers on the that /24.   Let's also say you have layer 3 interconnectivity as well for your remote offices to these 2 data centers, say over a MPLS solution, and these remote offices need to reach machines on that /24.   If the data centers both advertise the /24, only one preferred path would be chosen and you will run into performance issues if the machine happens to be living on the data center that doesnt have the preferred route.   

How have people addressed this?   Is it simply advertise smaller subnets and IP machines as appropriate (like /25 to DC A and a /25 to DC B though they are /24 inside the DC themselves)?

Thanks.

[Vasilii Mikhailovskii]

Hello.

To address the issue, there is a LISP accompany to OTV. 

[Aries Fernandes]

Its a valid doubt and what you refer to will bring in non-optimized routing into picture. But as mentioned below, LISP-ESM [extended subnet mode] will help overcome this hurdle. Basically if you see how OTV is placed, it complements HSRP and LISP very well.